scholarly journals Evidence that Noncoding RNA dutA Is a Multicopy Suppressor of Dictyostelium discoideum STAT Protein Dd-STATa

2007 ◽  
Vol 6 (6) ◽  
pp. 1030-1040 ◽  
Author(s):  
Nao Shimada ◽  
Takefumi Kawata
Keyword(s):  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Noncoding Rna ◽  
Target Genes ◽  
Wild Type Strain ◽  
Expression Patterns ◽  
Wild Type ◽  
Multicopy Suppressor ◽  
Phosphorylated Form ◽  
Multicopy Suppressors

ABSTRACT Dd-STATa, a Dictyostelium discoideum homologue of metazoan STAT transcription factors, is necessary for culmination. We created a mutant strain with partial Dd-STATa activity and used it to screen for unlinked suppressor genes. We screened approximately 450,000 clones from a slug-stage cDNA library for their ability to rescue the culmination defect when overexpressed. There were 12 multicopy suppressors of Dd-STATa, of which 4 encoded segments of a known noncoding RNA, dutA. Expression of dutA is specific to the pstA zone, the region where Dd-STATa is activated. In suppressed strains the expression patterns of several putative Dd-STATa target genes become similar to the wild-type strain. In addition, the amount of the tyrosine-phosphorylated form of Dd-STATa is significantly increased in the suppressed strain. These results indicate that partial copies of dutA may act upstream of Dd-STATa to regulate tyrosine phosphorylation by an unknown mechanism.

Action of a slowly hydrolysable cyclic AMP analogue on developing cells of Dictyostelium discoideum

1979 ◽  
Vol 35 (1) ◽  
pp. 321-338
Author(s):  
C. Rossier ◽  
G. Gerisch ◽  
D. Malchow
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Agar Plate ◽  
Cell Aggregation ◽  
Fruiting Bodies ◽  
Wild Type ◽  
Camp Analogue ◽  
Order Of Magnitude

Adenosine 3′,5′-cyclic phosphorothioate (cAMP-S) is a cyclic AMP (cAMP) analogue which is only slowly hydrolysed by phosphodiesterases of Dictyostelium discoideum. The affinity of cAMP-S to cAMP receptors at the cell surface is only one order of magnitude lower than that of cAMP. cAMP-S can replace cAMP as a stimulant with respect to all receptor-mediated responses tested, including chemotaxis and the induction of cAMP pulses. cAMP-S does not affect growth of D. discoideum but it blocks cell aggregation at a uniform concentration of 5 × 10(−7) M in agar plate cultures of strain NC-4 as well as its axenically growing derivative, Ax-2. Another wild-type strain of D. discoideum, v-12, is able to aggregate on agar plates supplemented with 1 mM cAMP-S. The development of Polysphondylium pallidum and P. violaceum is also highly cAMP-S resistant. In Ax-2 both differentiation from the growth phase to the aggregation-competent stage and chemotaxis are cAMP-S sensitive, whereas in v-12 only chemotaxis is inhibited. v-12 can still form streams of cohering cells and fruiting bodies when chemotaxis is inhibited by cAMP-S. Whereas cAMP induces differentiation into stalk cells at concentrations of 10(−3) or 10(−4) M, cAMP-S has the same effect in strain v-12 at the much lower concentration of 10(−6) M.

NEW LOCI IN DICTYOSTELIUM DISCOIDEUM DETERMINING PIGMENT FORMATION AND GROWTH ON BACILLUS SUBTILIS

Genetics ◽  
1980 ◽  
Vol 96 (1) ◽  
pp. 115-123
Author(s):  
James H Morrissey ◽  
Steven Wheeler ◽  
William F Loomis
Keyword(s):  
Bacillus Subtilis ◽  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Linkage Groups ◽  
New Mutation ◽  
Pigment Formation ◽  
Complementation Groups ◽  
First Time

ABSTRACT Seventeen independently isolated pigmentless (white) mutations in Dictyostelium discoideum are all recessive and fall into three complementation groups identifying two new whi loci in addition to the previously characterized whiA locus. whiB and whiC map to linkage groups III and IV, respectively. In addition, it was discovered that our laboratory stock of NC4, the wild-type strain from which these mutants were derived, has spontaneously lost the ability to grow on Bacillus subtilis. This new mutation, bsgB500, maps to linkage group VII and is not allelic to bsgA. bsgB500 is the first spontaneously derived mutation in D. discoideum that can be used to select heterozygous diploids, and for the first time allows genetic analysis to be routinely performed on strains derived from an unmutagenized background.

The age-dependent loss of cells from the rear of a Dictyostelium discoideum slug is not tip controlled

Development ◽  
1981 ◽  
Vol 61 (1) ◽  
pp. 61-67
Author(s):  
Elizabeth Smith ◽  
Keith L. Williams
Keyword(s):  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Organizer Region ◽  
Cell Loss ◽  
Wild Type ◽  
Reciprocal Transplants ◽  
Age Dependent ◽  
Dependent Cell ◽  
Cellular Slime

Young slugs of the cellular slime mould Dictyostelium discoideum drop small numbers of individual amoebae (∼ 10/mm) in the slime trail. With increased time of migration, slugs develop trailing tails and leave clumps of cells in their slime trails. Using reciprocal transplants between tips of young and old slugs and between a wild-type strain and an ‘aged'’ mutant it was shown that this age-dependent cell loss is due to changes in the bulk of cells comprising the slug, rather than to changes in the effectiveness of the tip (organizer region). Another property of the slug, the decision to continue migrating or form a fruiting body which is controlled by the tip, was less affected by age. This raises the possibility that cell autonomous properties of the slug are more subject to ageing than is the tip.

Movement of the multicellular slug stage of Dictyostelium discoideum: an analytical approach

Development ◽  
1987 ◽  
Vol 101 (2) ◽  
pp. 313-321 ◽  
Author(s):  
E.J. Breen ◽  
P.H. Vardy ◽  
K.L. Williams
Keyword(s):  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Analytical Approach ◽  
Wild Type Strain ◽  
Time Lapse ◽  
Wild Type ◽  
Forward Movement ◽  
Migration Rates ◽  
Video Recordings ◽  
In The Wild

Time-lapse video recordings of migrating multicellular slugs of Dictyostelium discoideum were subjected to image analysis. A transient ‘collar-like’ structure was identified at the anterior end of the slug. This collar remains stationary in the wild- type strain WS380B; it is observed shortly after the advancing tip contacts the substratum. Stationary collars formed approximately every 12min; they were matched with patterns revealed on the underside of slime trails with FITC-coupled monoclonal antibody MUD50. It is proposed that stationary collars are involved with the forward movement of the slug. The mutant strain HU2421 lacks the MUD50-epitope and forms collars which do not remain stationary but move backwards along the slug to collect at a ‘waist’ region. The slipping-collars observed in the mutant correlated with very slow migration rates. We propose that HU2421 moves slowly because it lacks traction.

scholarly journals CadA Negatively Regulates Escherichia coli O157:H7 Adherence and Intestinal Colonization

2008 ◽  
Vol 76 (11) ◽  
pp. 5072-5081 ◽  
Author(s):  
Roberto C. Vazquez-Juarez ◽  
Jeeba A. Kuriakose ◽  
David A. Rasko ◽  
Jennifer M. Ritchie ◽  
Melissa M. Kendall ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Cultured Cells ◽  
Expression Patterns ◽  
Gene Array ◽  
Rabbit Model ◽  
Gene Expression Patterns ◽  
Wild Type

ABSTRACT Adherence of pathogenic Escherichia coli strains to intestinal epithelia is essential for infection. For enterohemorrhagic E. coli (EHEC) serotype O157:H7, we have previously demonstrated that multiple factors govern this pathogen's adherence to HeLa cells (A. G. Torres and J. B. Kaper, Infect. Immun. 71:4985-4995, 2003). One of these factors is CadA, a lysine decarboxylase, and this protein has been proposed to negatively regulate virulence in several enteric pathogens. In the case of EHEC strains, CadA modulates expression of the intimin, an outer membrane adhesin involved in pathogenesis. Here, we inactivated cadA in O157:H7 strain 86-24 to investigate the role of this gene in EHEC adhesion to tissue-cultured monolayers, global gene expression patterns, and colonization of the infant rabbit intestine. The cadA mutant did not possess lysine decarboxylation activity and was hyperadherent to tissue-cultured cells. Adherence of the cadA mutant was nearly twofold greater than that of the wild type, and the adherence phenotype was independent of pH, lysine, or cadaverine in the media. Additionally, complementation of the cadA defect reduced adherence back to wild-type levels, and it was found that the mutation affected the expression of the intimin protein. Disruption of the eae gene (intimin-encoding gene) in the cadA mutant significantly reduced its adherence to tissue-cultured cells. However, adherence of the cadA eae double mutant was greater than that of an 86-24 eae mutant, suggesting that the enhanced adherence of the cadA mutant is not entirely attributable to enhanced expression of intimin in this background. Gene array analysis revealed that the cadA mutation significantly altered EHEC gene expression patterns; expression of 1,332 genes was downregulated and that of 132 genes was upregulated in the mutant compared to the wild-type strain. Interestingly, the gene expression variation shows an EHEC-biased gene alteration including intergenic regions. Two putative adhesins, flagella and F9 fimbria, were upregulated in the cadA mutant, suggestive of their association with adherence in the absence of the Cad regulatory mechanism. In the infant rabbit model, the cadA mutant outcompeted the wild-type strain in the ileum but not in the cecum or mid-colon, raising the possibility that CadA negatively regulates EHEC pathogenicity in a tissue-specific fashion.

scholarly journals The Campylobacter jejuni Response Regulator, CbrR, Modulates Sodium Deoxycholate Resistance and Chicken Colonization

2005 ◽  
Vol 187 (11) ◽  
pp. 3662-3670 ◽  
Author(s):  
Brian H. Raphael ◽  
Sonia Pereira ◽  
Gary A. Flom ◽  
Qijing Zhang ◽  
Julian M. Ketley ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Histidine Kinase ◽  
Bile Salts ◽  
Type Strain ◽  
Target Genes ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Sodium Deoxycholate ◽  
Wild Type ◽  
Bile Resistance

ABSTRACT Two-component regulatory systems play a major role in the physiological response of bacteria to environmental stimuli. Such systems are composed of a sensor histidine kinase and a response regulator whose ultimate function is to affect the expression of target genes. Response regulator mutants of Campylobacter jejuni strain F38011 were screened for sensitivity to sodium deoxycholate. A mutation in Cj0643, which encodes a response regulator with no obvious cognate histidine kinase, resulted in an absence of growth on plates containing a subinhibitory concentration of sodium deoxcholate (1%, wt/vol). In broth cultures containing 0.05% (wt/vol) sodium deoxycholate, growth of the mutant was significantly inhibited compared to growth of the C. jejuni F38011 wild-type strain. Complementation of the C. jejuni cbrR mutant in trans restored growth in both broth and plate cultures supplemented with sodium deoxycholate. Based on the phenotype displayed by its mutation, we designated the gene corresponding to Cj0643 as cbrR (Campylobacter bile resistance regulator). While the MICs of a variety of bile salts and other detergents for the C. jejuni cbrR mutant were lower, no difference was noted in its sensitivity to antibiotics or osmolarity. Finally, chicken colonization studies demonstrated that the C. jejuni cbrR mutant had a reduced ability to colonize compared to the wild-type strain. These data support previous findings that bile resistance contributes to colonization of chickens and establish that the response regulator, CbrR, modulates resistance to bile salts in C. jejuni.

scholarly journals Control of EpsE, the Phosphoglycosyltransferase Initiating Exopolysaccharide Synthesis in Streptococcus thermophilus, by EpsD Tyrosine Kinase

2006 ◽  
Vol 189 (4) ◽  
pp. 1351-1357 ◽  
Author(s):  
Zoran Minic ◽  
Corinne Marie ◽  
Christine Delorme ◽  
Jean-Michel Faurie ◽  
Gérald Mercier ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Phosphorylation Site ◽  
Gel Filtration ◽  
Streptococcus Thermophilus ◽  
Wild Type ◽  
Conserved Motif ◽  
Phosphorylated Form ◽  
In The Wild

ABSTRACT We studied the roles of Streptococcus thermophilus phosphogalactosyltransferase (EpsE) (the priming enzyme), tyrosine kinase (EpsD), phosphatase (EpsB), and a membrane-associated protein with no known biochemical function (EpsC) in exopolysaccharide (EPS) synthesis. These proteins are well-conserved among bacteria and are usually encoded by clustered genes. Exopolysaccharide synthesis took place in the wild-type strain and a mutant lacking EpsB but not in mutants lacking EpsC, EpsD, or EpsE. The three mutants unable to synthesize EPS lacked the EpsE phosphogalactosyltransferase activity, while the two EPS-synthesizing strains possessed this activity, showing that EpsC and EpsD are required for EpsE function. An EpsD phosphorylated form was found in all strains except the epsC mutant, indicating that EpsC is necessary for EpsD phosphorylation. Moreover, the phosphorylated form of EpsD, a supposedly cytoplasmic protein, was found to be associated with the plasma membrane, possibly due to interaction with EpsC. Finally, the EpsD and EpsE elution profiles in a gel filtration chromatography assay were similar, suggesting that these two proteins colocalize in the membrane. Mutation of Tyr200, predicted to be a phosphorylation site and present in a conserved motif in bacterial phosphoglycosyltransferases, led to EpsE inactivation. In contrast, mutation of Tyr162 or Tyr199 had no effect. Taken together, these data show that EpsD controls EpsE activity. Possible mechanisms for this control are discussed.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

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